生物材料穿隧發光二極體與可拉伸半導體隨機雷射之光電特性研究

Optoelectronics properties of tunneling light emitting devices and stretchable random lasers based on semiconductors and biomaterials

孫梓閔(Tzu-Min Sun)

指導教授 ： 陳永芳

國立臺灣大學/理學院/物理學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201600932

摘要

摘要
在這篇論文中，我們探討了可拉伸隨機雷射和生物啟發性發光二極體(LED)的光電特性。透過物理上的分析和直覺，將半導體和生物材料特有的性質應用在隨機雷射和發光二極體上，展現了在未來能有多方面應用的潛力。我們的結果可分為兩個主題，總結如下：
1. 可拉伸隨機雷射與可調控同調迴圈
可拉伸性在將來的實際應用上是一個關鍵，包含在穿戴式工具，健康監測器，和機器皮膚的領域上。許多能應對巨大應變變形的光學、電學科技已經被開發。自從雷射被發現，他在我們生活中扮演重要的角色，特別是在可拉伸設備的發展上。由此，經由實驗設計和元件製造，我們展示了一個可拉伸的隨機雷射與可調控的同調迴圈。為了闡明運作原理，我們將氧化鋅奈米刷轉印在PDMS基板的頂部，形成可拉伸隨機雷射的材料。不同於傳統的氧化鋅奈米桿，氧化鋅奈米刷不僅僅是發光材料和雷射散射中心，更可以提供Fabry–Pérot共振腔來提高雷射的強度。可拉伸的PDMS基板提供了額外的自由度，讓我們能改變奈米鋅的密度、機械式地調控隨機雷射的同調迴圈。我們發現，雷射的頻數會隨著施加在PDMS基板上的應力增加而有所增加，其原因可由各種不同構造的同調迴圈在拉伸過程被製造來解釋。此樣品可拉伸高達30%並可承受高於100次的循環拉伸且保持雷射強度不減。這個結果對於將來人造智慧拉伸的裝置是一個重大的進展。

2. 高效能金屬/雞蛋白/半導體穿隧二極體
由於對環境友善、便宜、易取得且製造過程簡易，生物材料在光學和電學儀器的應用上吸引了極大的關注。在此篇論文中，我們使用了生物材料，雞蛋白，作為金屬-絕緣體-半導體(MIS)發光二極體(LED)的絕緣體，此樣品包含氮化鎵薄膜和金屬電極。在MIS LED樣品中，絕緣體作為能量障壁，使自由載子(電動或電子)累積在金屬絕緣體交界處並以此增加複合速率。有了更高的複合速率，LED裝置就能在更低的電流下運作，並提供更高的發光強度。和傳統的絕緣材料，如二氧化矽和氧化鎂相比，雞蛋白不僅僅能作為能量障壁，還提供的生物相容性的優點。除此之外，雞蛋白MIS LED樣品展現了良好的穩定性。研究發現，載子從金屬穿隧至氮化鎵薄膜的複合過程可由Frenkel-Poole效應解釋。源自各個不同官能基的能階可以有效的輔助穿隧效應並降低工作電壓。

關鍵字

隨機雷射 ； 可拉伸 ； 可調控 ； 同調迴圈 ； 氧化鋅奈米結構 ； Fabry–Pérot共振 ； 生物材料 ； 二極體 ； p型氮化鎵 ； 雞蛋白 ； Frenkel-Poole穿隧

並列摘要

Abstract
In this thesis, we investigate the optoelectronic properties of stretchable random laser and bio-inspired light emitting diodes (LEDs). By physical analysis and intuition, the fascinating properties of semiconductors and bio-materials are applied to random laser and LED devices, which shows the potentials for diverse application in the future. Our results are classified as two topics and summarized as the followings:
1. Stretchable Random Lasers with Tunable Coherent Loops
Stretchability represents a key feature for the emerging world of realistic applications in areas, including wearable gadgets, health monitors, and robotic skins. Many optical and electronic technologies that can respond to large strain deformations have been developed. Laser plays a very important role in our daily life since it was discovered, which is highly desirable for the development of stretchable devices. Herein, stretchable random lasers with tunable coherent loops are designed, fabricated, and demonstrated. To illustrate our working principle, the stretchable random laser is made possible by transferring unique ZnO nanobrushes on top of polydimethylsiloxane (PDMS) elastomer substrate. Apart from the traditional gain material of ZnO nanorods, ZnO nanobrushes were used as optical gain materials so they can serve as scattering centers and provide the Fabry–Pérot cavity to enhance laser action. The stretchable PDMS substrate gives the degree of freedom to mechanically tune the coherent loops of the random laser action by changing the density of ZnO nanobrushes. It is found that the number of laser modes increases with increasing external strain applied on the PDMS substrate due to the enhanced possibility for the formation of coherent loops. The device can be stretched by up to 30% strain and subjected to more than 100 cycles without loss in laser action. The result shows a major advance for the further development of man-made smart stretchable devices.
2. High-performance Metal/Albumen/Semiconductor Tunneling Light Emitting Devices
Biomaterials have attracted a great deal of attention for various kinds of devices due to their environmentally friendly and accessible processes. In this paper, chicken albumen is used as the insulator in metal-insulator-semiconductor (MIS) light emitting diodes (LEDs). The insulator in MIS LED devices functions as an energy barrier, which allows free carriers to accumulate and thus increases the recombination rate near the interface. With a higher recombination rate, the LED device can work under a lower injection current and provide stronger light emission intensity. Compared with traditional insulating materials, albumen not only plays the role of an energy barrier, but also holds a decided advantage of bio-comparable capability. In addition, albumen based MIS LED devices exhibit an excellent stability. It is found that charge carriers tunneling from metal to semiconductor thin films based on the Frenkel-Poole effect is responsible for the recombination process. The energy states arising from various functional groups containing in chicken albumen can effectively assist the tunneling process and reduce the working voltage. A proof-of-concept demonstration of our advanced approach has been performed for GaN and AlGaN deep UV LEDs.

並列關鍵字

random laser ； stretchable ； tunable ； coherent loop ； ZnO nanostructure ； Fabry–Pérot resonance ； biomaterial ； light emitting diode ； p-GaN ； albumen ； Frenkel-Poole tunneling

參考文獻

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